Multi-layer film with improved modulus properties

ABSTRACT

The invention relates to a multi-layer, preferably co-extruded, plastic film with improved modulus properties, which is suitable, in particular, for producing three-dimensionally shaped articles.

FIELD OF THE INVENTION

The invention relates to a multi-layer, preferably co-extruded, plasticfilm with improved modulus properties, which is suitable, in particular,for producing three-dimensionally formed products e.g. by athermo-forming process.

BACKGROUND OF THE INVENTION

For several applications, in particular medical applications, it is ofmajor interest that three-dimensionally formed articles, which have beenobtained by forming a plastic film, are stable in its three-dimensionalform in presence of a wet or humidity environment. Additionally, greatdemands are made of the plastic films, particularly with respect to thetensile modulus thereof, since the formed articles have to exertsufficient tension during the time of its use.

In the past, single-layer films, for example, consisting of a varity ofthermoplastic materials have been employed for applications in wet orhumidity environment, which, however, have the disadvantage that despitea high tensile modulus prior to the start of the use this tensilemodulus falls off greatly during the period of its use, so thatfrequently the desired success of the use is not obtained as planned anda reworking of the three-dimensionally formed article becomes necessary.Such a reworking is very costly.

In order to avoid this disadvantage, a demand has therefore existed forplastic films for the production three-dimensionally shaped products,with which the distinct drop in the tensile modulus during the period ofthe use in wet environment can be diminished.

SUMMARY OF THE INVENTION

The object that underlay the present invention accordingly consisted inproviding suitable plastic films for the production ofthree-dimensionally shaped products, with which the distinct drop in thetensile modulus during the period of the its use can be diminished.

Surprisingly, it has been found that a multi-layer, preferablythree-layer, plastic film containing a core layer comprising apolycarbonate or copolycarbonate and/or a polyester or copolyesterbetween two layers comprising a thermoplastic polyurethane and/or apolyester or copolyester with special properties eliminates thedisadvantages listed above.

DETAILED DESCRIPTION OF THE INVENTION

The subject-matter of the present invention is therefore a multi-layerplastic film, characterised in that

-   -   it has a core layer A containing at least one polycarbonate or        copolycarbonate and/or a polyester or copolyester having a glass        transition temperature T_(g) from 80° C. to 200° C., preferably        from 80° C. to 170° C., more preferably from 80° C. to 150° C.    -   and this core layer is located between two outer layers B        containing at least one thermoplastic polyurethane and/or        polyester or copolyester exhibiting a hardness from 45 Shore D        to 85 Shore D.

Glass transition temperatures T_(g) are determined by means ofdifferential scanning calorimetry (DSC) according to standard DIN EN61006 at a heating-rate of 20 K/min with definition of T_(g) as themidpoint temperature (tangent method).

Preferably according to the present invention the core layer A comprisesat least one polyester or copolyester, wherein the inherent viscosity ofthe polyester or copolyester amounts to 0.50 dL/g to 1.20 dL/g and thepolyester or copolyester exhibits a glass transition temperature T_(g)from 80° C. to 150° C.

The inherent viscosity is determined in 60/40 (wt/wt)phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.

Preferably according to the present invention the two outer layers Bcomprise at least one thermoplastic polyurethane exhibiting a hardnessfrom 45 Shore D to 85 Shore D.

In a preferred embodiment of the present invention the multi-layerplastic film

-   -   has a core layer A containing at least one polyester or        copolyester having an inherent viscosity from 0.50 dL/g to 1.20        dL/g and a glass transition temperature T_(g) from 80° C. to        150° C.    -   and this core layer A is located between two outer layers B        containing at least one thermoplastic polyurethane exhibiting a        hardness from 45 Shore D to 85 Shore D.

Suitable and preferred polyester or copolyester for the core layer A arepoly- or copolycondensates of terephthalic acid or naphthalenedicarboxylic acid, such as, for example and preferably, poly- orcopolyethylene terephthalate (PET or CoPET), glycol-modified PET (PETG)or poly- or copolybutylene terephthalate (PBT or CoPBT), poly- orcopolyethylene naphthalate (PEN or CoPEN).

Suitable and preferred polycarbonates or copolycarbonates for the corelayer A are in particular polycarbonates or copolycarbonates withaverage molecular weights M_(w) of from 500 to 100,000, preferably from10,000 to 80,000, particularly preferably from 15,000 to 40,000.

Additionally, blends containing at least one such polycarbonate orcopolycarbonate are suitable and preferred for the core layer A. Blendsof the abovementioned polycarbonates or copolycarbonates with at leastone poly- or copolycondensate of terephthalic acid, in particular atleast one such poly- or copolycondensate of terephthalic acid withaverage molecular weights M_(w) of from 10,000 to 200,000, preferablyfrom 26,000 to 120,000, are furthermore also suitable and preferred. Inparticularly preferred embodiments of the invention, the blend is ablend of polycarbonate or copolycarbonate with poly- or copolybutyleneterephthalate. Such a blend of polycarbonate or copolycarbonate withpoly- or copolybutylene terephthalate can preferably be one with 1 to 90wt. % of polycarbonate or copolycarbonate and 99 to 10 wt. % of poly- orcopolybutylene terephthalate, preferably with 1 to 90 wt. % ofpolycarbonate and 99 to 10 wt. % of polybutylene terephthalate, thecontents adding up to 100 wt. %. Such a blend of polycarbonate orcopolycarbonate with poly- or copolybutylene terephthalate canparticularly preferably be one with 20 to 85 wt. % of polycarbonate orcopolycarbonate and 80 to 15 wt. % of poly- or copolybutyleneterephthalate, preferably with 20 to 85 wt. % of polycarbonate and 80 to15 wt. % of polybutylene terephthalate, the contents adding up to 100wt. %. Such a blend of polycarbonate or copolycarbonate with poly- orcopolybutylene terephthalate can very particularly preferably be onewith 35 to 80 wt. % of polycarbonate or copolycarbonate and 65 to 20 wt.% of poly- or copolybutylene terephthalate, preferably with 35 to 80 wt.% of polycarbonate and 65 to 20 wt. % of polybutylene terephthalate, thecontents adding up to 100 wt. %.

In preferred embodiments, particularly suitable polycarbonates orcopolycarbonates are aromatic polycarbonates or copolycarbonates.

The polycarbonates or copolycarbonates can be linear or branched in aknown manner.

The preparation of these polycarbonates can be carried out in a knownmanner from diphenols, carbonic acid derivatives, optionally chainterminators and optionally branching agents. Details of the preparationof polycarbonates have been laid down in many patent specifications forabout 40 years. Reference may be made here by way of example merely toSchnell, “Chemistry and Physics of Polycarbonates”, Polymer Reviews,volume 9, Interscience Publishers, New York, London, Sydney 1964, to D.Freitag, U. Grigo, P. R. Müler, H. Nouvertne', BAYER AG,“Polycarbonates” in Encyclopedia of Polymer Science and Engineering,volume 11, second edition, 1988, pages 648-718 and finally to Dres. U.Grigo, K. Kirchner and P. R. Müller “Polycarbonate” in Becker/Braun,Kunststoff-Handbuch, volume 3/1, Polycarbonate, Polyacetale, Polyester,Celluloseester, Carl Hanser Verlag Munich, Vienna 1992, pages 117-299.

Suitable diphenols can be, for example, dihydroxyaryl compounds of thegeneral formula) III)

HO—Z—OH  (III)

wherein Z is an aromatic radical having 6 to 34 C atoms, which cancontain one or more optionally substituted aromatic nuclei and aliphaticor cycloaliphatic radicals or alkylaryls or hetero atoms as bridgemembers.

Particularly preferred dihydroxyaryl compounds are resorcinol,4,4′-dihydroxydiphenyl, bis-(4-hydroxyphenyl)-diphenyl-methane,1,1-bis-(4-hydroxyphenyl)-1-phenyl-ethane,bis-(4-hydroxyphenyl)-1-(1-naphthyl)-ethane,bis-(4-hydroxyphenyl)-1-(2-naphthyl)-ethane,2,2-bis-(4-hydroxyphenyl)-propane,2,2-bis(3,5-dimethyl-4-hydroxyphenyl)-propane,1,1-bis-(4-hydroxyphenyl)-cyclohexane,1,1-bis-(3,5-dimethyl-4-hydroxyphenyl)-cyclohexane,1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane,1,1′-bis-(4-hydroxyphenyl)-3-diisopropyl-benzene and1,1′-bis-(4-hydroxyphenyl)-4-diisopropyl-benzene.

Very particularly preferred dihydroxyaryl compounds are4,4′-dihydroxydiphenyl, 2,2-bis-(4-hydroxyphenyl)-propane andbis-(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane.

A very particularly preferred copolycarbonate can be prepared using1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane and2,2-bis-(4-hydroxyphenyl)-propane.

Suitable carbonic acid derivatives can be, for example, phosgene ordiaryl carbonates of the general formula (IV)

wherein

-   R, R′ and R″ independently of each another are identical or    different and represent hydrogen, linear or branched C₁-C₃₄-alkyl,    C₇-C₃₄-alkylaryl or C₆-C₃₄-aryl, and R can furthermore also denote    —COO—R′″, wherein R′″ represents hydrogen, linear or branched    C₁-C₃₄-alkyl, C₇-C₃₄-alkylaryl or C₆-C₃₄-aryl.

Particularly preferred diaryl compounds are diphenyl carbonate,4-tert-butylphenyl phenyl carbonate, di-(4-tert-butylphenyl) carbonate,biphenyl-4-yl phenyl carbonate, di-(biphenyl-4-yl) carbonate,4-(1-methyl-1-phenylethyl)-phenyl phenyl carbonate,di-[4-(1-methyl-1-phenylethyl)-phenyl] carbonate and di-(methylsalicylate) carbonate.

Diphenyl carbonate is very particularly preferred.

Either one diaryl carbonate or different diaryl carbonates can be used

One or more monohydroxyaryl compound(s) which has/have not been used forthe preparation of the diaryl carbonate(s) used can additionally beemployed, for example, as chain terminators to control or vary the endgroups. These can be those of the general formula (V)

wherein

-   R^(A) represents linear or branched C₁-C₃₄-alkyl, C₇-C₃₄-alkylaryl,    C₆-C₃₄-aryl or —COO—R^(D), wherein R^(D) represents hydrogen, linear    or branched C₁-C₃₄-alkyl, C₇-C₃₄-alkylaryl or C₆-C₃₄-aryl, and-   R^(B), R^(c) independently of each other are identical or different    and represent hydrogen, linear or branched C₁-C₃₄-alkyl,    C₇-C₃₄-alkylaryl or C₆-C₃₄-aryl.    4-tert-Butylphenol, 4-iso-octylphenol and 3-pentadecylphenol are    preferred.

Suitable branching agents can be compounds with three and morefunctional groups, preferably those with three or more hydroxyl groups.

Preferred branching agents are3,3-bis-(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole and1,1,1-tris-(4-hydroxyphenyl)-ethane.

For the core layer A poly- or copolyalkylene terephthalates or poly- orcopolyalkylene naphthalates are suitable in preferred embodiments of theinvention as poly- or copolycondensates of terephthalic acid ornaphthalene dicarboxylic acid. Suitable poly- or copolyalkyleneterephthalates or poly- or copolyalkylene naphthalates are for examplereaction products of aromatic dicarboxylic acids or reactive derivativesthereof (for example dimethyl esters or anhydrides) and aliphatic,cycloaliphatic or araliphatic diols and mixtures of these reactionproducts.

As used herein, the term “terephthalic acid” is intended to includeterephthalic acid itself and residues thereof as well as any derivativeof terephthalic acid, including its associated acid halides, esters,half-esters, salts, half-salts, anhydrides, mixed anhydrides, ormixtures thereof or residues thereof useful in a reaction process with adiol to make polyester. In one embodiment, the esters are chosen from atleast one of the following: methyl, ethyl, propyl, isopropyl, and phenylesters. In one embodiment, terephthalic acid may be used as the startingmaterial. In another embodiment, dimethyl terephthalate may be used asthe starting material. In another embodiment, mixtures of terephthalicacid and dimethyl terephthalate may be used as the starting materialand/or as an intermediate material.

As used herein, the term “naphthalene dicarboxylic acid” is intended toinclude naphthalene dicarboxylic acid itself and residues thereof aswell as any derivative of naphthalene dicarboxylic acid, including itsassociated acid halides, esters, half-esters, salts, half-salts,anhydrides, mixed anhydrides, or mixtures thereof or residues thereofuseful in a reaction process with a diol to make polyester. In oneembodiment, the esters are chosen from at least one of the following:methyl, ethyl, propyl, isopropyl, and phenyl esters. In one embodiment,naphthalene dicarboxylic acid may be used as the starting material. Inanother embodiment, the dimethylester of naphthalene dicarboxylic acidmay be used as the starting material. In another embodiment, mixtures ofterephthalic acid and the dimethylester of naphthalene dicarboxylic acidmay be used as the starting material and/or as an intermediate material.

In addition to terephthalic acid or naphthalene dicarboxylic acid, thedicarboxylic acid component of the poly- or copolyester useful in theinvention can optionally comprises up to 30 mole %, preferably up to 20mole %, more preferably up to 10 mole %, most preferably up to 5 mole %of one or more modifying aromatic dicarboxylic acids. In one preferredembodiment the dicarboxylic acid component of the poly- or copolyesteruseful in the invention comprise up to 1 mole % of one or more modifyingaromatic dicarboxylic acids. Yet in another preferred embodiment thedicarboxylic acid component of the poly- or copolyester useful in theinvention comprises 0 mole % modifying aromatic dicarboxylic acids.Thus, if present, it is contemplated that the amount of one or moremodifying aromatic dicarboxylic acids can range from any of thesepreceding endpoint values including, for example, from 0.01 to 30 mole%, preferably from 0.01 to 20 mole %, more preferably from 0.01 to 10mole %, most preferably from 0.01 to 5 mole % and in a preferredembodiment from 0.01 to 1 mole. In one embodiment, modifying aromaticdicarboxylic acids that may be used in the present invention include butare not limited to those having up to 20 carbon atoms, preferably having8 to 14 carbon atoms, and which can be linear, para-oriented, orsymmetrical. Examples of modifying aromatic dicarboxylic acids which maybe used in this invention include, but are not limited to, phthalicacid, isophthalic acid, 4,4′-biphenyldicarboxylic acid, 1,4-, 1,5-,2,6-, 2,7-naphthalenedicarboxylic acid (in case of poly- orcopolyalkylene terephthalates), terephthalic acid (in case of poly- orcopolyalkylene naphthalates) and trans-4,4′-stilbenedicarboxylic acid,and esters thereof.

The carboxylic acid component of the copolyesters useful in theinvention can optionally be further modified with up to 10 mole %, suchas up to 5 mole % or preferably up to 1 mole % of one or more aliphaticdicarboxylic acids containing 2 to 16 carbon atoms, such as, forexample, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic,sebacic, cyclohexane diacetic and dodecanedioic dicarboxylic acids. Yetanother embodiment contains 0 mole % modifying aliphatic dicarboxylicacids. Thus, if present, it is contemplated that the amount of one ormore modifying aliphatic dicarboxylic acids can range from any of thesepreceding endpoint values including, for example, from 0.01 to 10 mole %and preferably from 0.1 to 10 mole %.

Preferred poly- or copolyalkylene terephthalates or poly- orcopolyalkylene naphthalates contain at least 70 mole %, preferably atleast 80 mole % ethylene glycol,butanediol-1,4,2,2,4,4-tetramethyl-1,3-cyclobutanediol and/or1,4-cyclohexanedimethanol residues, relative to the diol component.

The preferred poly- or copolyalkylene terephthalates or poly- orcopolyalkylene naphthalates can contain in addition to ethylene glycol,butanediol-1,4,2,2,4,4-tetramethyl-1,3-cyclobutanediol and/or1,4-cyclohexanedimethanol residues up to 30 mole %, preferably up to 20mole % of other aliphatic diols having 3 to 12 C atoms or cycloaliphaticdiols having 6 to 21 C atoms, for example radicals ofpropanediol-1,3,2-ethylpropanediol-1,3, neopentyl glycol,pentanediol-1,5, hexanediol-1,6, cyclohexanedimethanol-1,4,3-methylpentanediol-2,4,2-methylpentanediol-2,4,2,2,4-trimethylpentanediol-1,3and 2-ethylhexanediol-1,6,2,2-diethylpropanediol-1,3,hexanediol-2,5,1,4-di-([beta]-hydroxyethoxy)-benzene,2,2-bis-(4-hydroxycyclohexyl)propane,2,4-dihydroxy-1,1,3,3-tetramethylcyclobutane,2,2-bis-(3-[beta]-hydroxyethoxyphenyl)propane and2,2-bis-(4-hydroxypropoxyphenyl)propane (cf. DE-OS 24 07 674, 24 07 776,27 15 932).

The poly- or copolyesters of the invention can comprise from 0 to 10mole %, for example, from 0.01 to 5 mole % based on the total molepercentages of either the diol or diacid residues, respectively, of oneor more residues of a branching monomer, also referred to herein as abranching agent, having 3 or more carboxyl substituents, hydroxylsubstituents, or a combination thereof. In certain embodiments, thebranching monomer or agent may be added prior to and/or during and/orafter the polymerization of the poly- or copolyester. The poly- orcopolyester(s) useful in the invention can thus be linear or branched.In preferred embodiments the poly- or copolyester(s) useful in theinvention are linear and thus do not contain such branching agent.

Examples of branching monomers, if present, include, but are not limitedto, multifunctional acids or multifunctional alcohols such astrimellitic acid, trimellitic anhydride, pyromellitic dianhydride,trimethylolpropane, glycerol, pentaerythritol, citric acid, tartaricacid, 3-hydroxyglutaric acid and the like. In one embodiment, thebranching monomer residues can comprise 0.1 to 0.7 mole percent of oneor more residues chosen from at least one of the following: trimelliticanhydride, pyromellitic dianhydride, glycerol, sorbitol,1,2,6-hexanetriol, pentaerythritol, trimethylolethane, and/or trimesicacid. The branching monomer may be added to the copolyester reactionmixture or blended with the copolyester in the form of a concentrate asdescribed, for example, in U.S. Pat. Nos. 5,654,347 and 5,696,176.

Preferred poly- or copolyalkylene terephthalates or poly- orcopolyalkylene naphthalates contain at least 70 mole %, preferably 80mole % terephthalic acid or naphthalene dicarboxylic acid residues,relative to the dicarboxylic acid component, and at least 70 mole %,preferably at least 80 mole % ethylene glycol,butanediol-1,4,2,2,4,4-tetramethyl-1,3-cyclobutanediol and/or1,4-cyclohexanedimethanol residues, relative to the diol component.

In one particularly preferred embodiment the core layer A comprises atleast one copolyester produced solely from terephthalic acid andreactive derivatives thereof (for example dialkyl esters thereof) andethylene glycol and/or butanediol-1,4.

In another particularly preferred embodiment the core layer A comprisesat least one blend of polycarbonate or copolycarbonate with poly- orcopolybutylene terephthalate with 1 to 90 wt. % of polycarbonate orcopolycarbonate and 99 to 10 wt. % of poly- or copolybutyleneterephthalate, preferably with 35 to 80 wt. % of polycarbonate and 65 to20 wt. % of polybutylene terephthalate, the contents adding up to 100wt. %.

In another particularly preferred embodiment of the present inventionthe core layer A comprises at least one copolyester that exhibitsresidues from

-   -   (a) a dicarboxylic acid component comprising        -   i) 70 mole % to 100 mole % terephthalic acid residues,        -   ii) 0 mole % to 30 mole % aromatic dicarboxylic acid            residues with up to 20 carbon atoms, and        -   iii) 0 mole % to 10 mole % aliphatic dicarboxylic acid            residues with up to 16 carbon atoms, and    -   (b) a diol component comprising        -   i) 5 mole % to 50 mole %            2,2,4,4-tetramethyl-1,3-cyclobutanediol residues, and        -   ii) 50 mole % to 95 mole % 1,4-cyclohexanedimethanol            residues,            wherein the sum of the mole % of residues i)-iii) of the            dicarboxylic acid component amounts to 100 mole % and the            sum of the mole % of residues i) and ii) of the diol            component amounts to 100 mole %.

The two outer layers B preferably comprise at least one thermoplasticpolyurethane exhibiting a hardness from 45 Shore D to 85 Shore D.

Particularly preferably such at least one thermoplastic polyurethane isobtainable from

-   -   a) one or more linear polyether diols with mean molecular        weights from 500 g/mol to 10,000 g/mol, preferably 500 g/mol to        6000 g/mol, and, on average, in each instance at least 1.8 and        at most 3.0, preferably 1.8 to 2.2, Tserevitinov-active hydrogen        atoms    -   b) one or more organic diisocyanates,    -   c) one or more diol chain-extenders with molecular weights from        60 g/mol to 500 g/mol and with, on average, 1.8 to 3.0        Tserevitinov-active hydrogen atoms    -   in the presence of    -   d) optionally, one or more catalysts    -   with addition of    -   e) optionally, auxiliary substances and additives,        wherein the molar ratio of the NCO groups in b) to the groups        in a) and c) that are reactive towards isocyanate amounts to        0.85:1 to 1.2:1, preferably 0.9:1 to 1.1:1.

In a particularly preferred embodiment of the present application themulti-layer plastic film is characterised in that

-   -   it has a core layer A containing at least one copolyester that        exhibits residues from        -   (a) a dicarboxylic acid component comprising            -   i) 70 mole % to 100 mole % terephthalic acid residues,            -   ii) 0 mole % to 30 mole % aromatic dicarboxylic acid                residues with up to 20 carbon atoms, and            -   iii) 0 mole % to 10 mole % aliphatic dicarboxylic acid                residues with up to 16 carbon atoms, and        -   (b) a diol component comprising            -   i) 5 mole % to 50 mole %                2,2,4,4-tetramethyl-1,3-cyclobutanediol residues, and            -   ii) 50 mole % to 95 mole % 1,4-cyclohexanedimethanol                residues,        -   wherein the sum of the mole % of residues i)-iii) of the            dicarboxylic acid component amounts to 100 mole % and the            sum of the mole % of residues i) and ii) of the diol            component amounts to 100 mole %        -   and wherein the inherent viscosity of the copolyester            amounts to 0.50 dL/g to 1.20 dL/g and the copolyester            exhibits a glass transition temperature T_(g) from 80° C. to            150° C.,        -   and this core layer is located between two outer layers B            containing at least one thermoplastic polyurethane, the            thermoplastic polyurethane exhibiting a hardness from 45            Shore D to 85 Shore D and being obtainable from        -   a) one or more linear polyether diols with mean molecular            weights from 500 g/mol to 10,000 g/mol, preferably 500 g/mol            to 6000 g/mol, and, on average, in each instance at least            1.8 and at most 3.0, preferably 1.8 to 2.2,            Tserevitinov-active hydrogen atoms        -   b) one or more organic diisocyanates,        -   c) one or more diol chain-extenders with molecular weights            from 60 g/mol to 500 g/mol and with, on average, 1.8 to 3.0            Tserevitinov-active hydrogen atoms        -   in the presence of        -   d) optionally, one or more catalysts        -   with addition of        -   e) optionally, auxiliary substances and additives,        -   wherein the molar ratio of the NCO groups in b) to the            groups in a) and c) that are reactive towards isocyanate            amounts to 0.85:1 to 1.2:1, preferably 0.9:1 to 1.1:1.

The film according to the invention surprisingly exhibits a distinctlysmaller drop in the tensile modulus under wet or humidity conditions.Moreover, the three-dimensional shaped articles made from such a filmaccording to the invention are stable in its three-dimensional shapeunder such conditions.

Thermoplastic polyurethanes (TPU) are mostly constructed from linearpolyols (macrodiols) such as polyester diols, polyether diols orpolycarbonate diols, organic diisocyanates and short-chain, mostlydifunctional, alcohols (chain-extenders). They may be producedcontinuously or discontinuously. The most well-known productionprocesses are the belt process (GB-A 1,057,018) and the extruder process(DE-A 1 964 834).

The thermoplastic polyurethanes preferably employed in accordance withthe invention are reaction products formed from the aforementioned

a) polyether diols

b) organic diisocyanates

c) chain-extenders.

By way of diisocyanates b), use may be made of aromatic, aliphatic,araliphatic, heterocyclic and cycloaliphatic diisocyanates or mixturesof these diisocyanates (cf. HOUBEN-WEYL “Methoden der organischenChemie”, Volume E20 “Makromolekulare Stoffe”, Georg Thieme Verlag,Stuttgart, N.Y. 1987, pp 1587-1593 or “Justus Liebigs Annalen derChemie”, 562, pages 75 to 136).

In detail, let the following be mentioned in exemplary manner: aliphaticdiisocyanates, such as hexamethylene diisocyanate, cycloaliphaticdiisocyanates, such as isophorone diisocyanate, 1,4-cyclohexanediisocyanate, 1-methyl-2,4-cyclohexane diisocyanate and1-methyl-2,6-cyclohexane diisocyanate and also the corresponding isomermixtures, 4,4′-dicyclohexylmethane diisocyanate,2,4′-dicyclohexylmethane diisocyanate and 2,2′-dicyclohexylmethanediisocyanate and also the corresponding isomer mixtures, aromaticdiisocyanates, such as 2,4-toluylene diisocyanate, mixtures consistingof 2,4-toluylene diisocyanate and 2,6-toluylene diisocyanate,4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane—diisocyanate and2,2′-diphenylmethane diisocyanate, mixtures consisting of2,4′-diphenylmethane diisocyanate and 4,4′-diphenylmethane diisocyanate,urethane-modified liquid 4,4′-diphenylmethane diisocyanates and2,4′-diphenylmethane-diisocyanates,4,4′-diisocyanatodiphenylethane-(1,2) and 1,5-naphthylene diisocyanate.Use is preferentially made of 1,6-hexamethylene diisocyanate, isophoronediisocyanate, dicyclohexylmethane-4,4′-diisocyanate,diphenylmethane-diisocyanate isomer mixtures with a content of4,4′-diphenylmethane diisocyanate of more than 96 wt. % and, inparticular, 4,4′-diphenylmethane diisocyanate and 1,5-naphthylenediisocyanate. The stated diisocyanates may find application individuallyor in the form of mixtures with one another. They may also be usedtogether with up to 15 wt. % (calculated with respect to the totalquantity of diisocyanate) of a polyisocyanate, for exampletriphenylmethane-4,4′,4″-triisocyanate or polyphenyl-polymethylenepolyisocyanates.

In the case of the organic diisocyanate(s) b) it is preferably aquestion of one or more isocyanate(s) selected from the group containing4,4′-diphenyl-methane diisocyanate, isophorone diisocyanate,dicyclohexylmethane-4,4′-diiso-cyanate and 1,6-hexamethylenediisocyanate.

Tserevitinov-active polyether diols a) are those with, on average, atleast 1.8 to at most 3.0, preferably 1.8 to 2.2, Tserevitinov-activehydrogen atoms.

Designated as Tserevitinov-active hydrogen atoms are all hydrogen atomsbonded to N, O or S that yield methane by conversion withmethylmagnesium halide in accordance with a process discovered byTserevitinov. The determination takes place after the Tserevitinovreaction, whereby methylmagnesium iodide is converted with the compoundto be investigated and reacts with acid hydrogen to form a magnesiumsalt and the corresponding hydrocarbon. The methane arising isdetermined by gas-volumetric analysis.

Suitable such polyether diols can be produced by one or more alkyleneoxides with 2 to 4 carbon atoms in the alkylene residue being convertedwith a starter molecule that contains two active hydrogen atoms inbonded form. By way of alkylene oxides, let the following be mentioned,for example: ethylene oxide, 1,2-propylene oxide, epichlorohydrin,1,2-butylene oxide and 2,3-butylene oxide. The alkylene oxides may beused individually, alternately in succession or as mixtures. By way ofstarter molecules there enter into consideration, for example: water,amino alcohols, such as N-alkyldiethanolamines, for exampleN-methyldiethanolamine, and diols such as ethylene glycol, 1,3-propyleneglycol, 1,4-butanediol and 1,6-hexanediol. Optionally, mixtures ofstarter molecules may also be employed. Suitable polyether diols arefurthermore the hydroxyl-group-containing polymerisation products oftetrahydrofuran and/or of 1,3-propylene glycol. Trifunctional polyethersin proportions from 0 wt. % to 30 wt. %, relative to the bifunctionalpolyethers, may also be employed, but at most in such quantity that aproduct arises that is still thermoplastically workable.

The polyether diols preferentially possess number-average molecularweights M_(n) from 500 g/mol to 8000 g/mol, particularly preferably 500g/mol to 6000 g/mol. They may find application both individually and inthe form of mixtures with one another.

The number-average molecular weights M_(n) can be determined withend-group determination, such as determination of hydroxyl numbersaccording to ASTM D 4274.

Tserevitinov-active chain-extenders c) are so-called chain-extensionagents and possess, on average, 1.8 to 3.0 Tserevitinov-active hydrogenatoms and have a number-average molecular weight from 60 g/mol to 500g/mol. Such agents are understood to be—besides compounds exhibitingamino groups, thiol groups or carboxyl groups—those with two to three,preferably two, hydroxyl groups. Hydroxyl compounds with two to three,preferably two, hydroxyl groups are particularly preferred aschain-extenders.

Employed by way of chain-extension agents are, for example andpreferably, diols or diamines with a molecular weight from 60 g/mol to500 g/mol, preferentially aliphatic diols with 2 to 14 carbon atoms,such as, for example, ethanediol, 1,2-propanediol, 1,3-propanediol,1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol,diethylene glycol and dipropylene glycol. Also suitable, however, arediesters of terephthalic acid with glycols with 2 to 4 carbon atoms, forexample terephthalic acid-bis-ethylene glycol or terephthalicacid-bis-1,4-butanediol, hydroxyalkylene ethers of hydroquinone, forexample 1,4-di(β-hydroxyethyl)hydroquinone, ethoxylated bisphenols, forexample 1,4-di(β-hydroxyethyl)bisphenol A, (cyclo)aliphatic diamines,such as isophoronediamine, ethylenediamine, 1,2-propylenediamine,1,3-propylenediamine, N-methylpropylene-1,3-diamine,N,N′-dimethylethylenediamine, and aromatic diamines, such as2,4-toluylenediamine, 2,6-toluylenediamine,3,5-diethyl-2,4-toluylenediamine or 3,5-diethyl-2,6-toluylenediamine orprimary mono-, di-, tri- or tetraalkyl-substituted4,4′-diaminodiphenylmethanes. Particularly preferably, use is made of1,2-ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol,1,6-hexanediol, 1,4-di(β-hydroxyethyl)hydroquinone or1,4-di(β-hydroxyethyl)bisphenol A by way of chain-extenders. Mixtures ofthe aforementioned chain-extenders may also be employed. In addition,relatively small quantities of triols may also be added.

The number-average molecular weights M_(n) can be determined withend-group determination, such as determination of hydroxyl numbersaccording to ASTM D 4274.

In the case of the diol chain-extender(s) c) it is preferably a questionof one or more selected from the group containing 1,4-butanediol,1,3-propanediol, 1,2-propanediol, 1,2-ethylene glycol, 1,6 hexanediol,1,4-di(β-hydroxyethyl)hydro-quinone and 1,4-di(β-hydroxyethyl)bisphenolA.

Reactive groups towards isocyanate in a) and c) are in particularTserevitinov-active hydrogen atoms containing groups.

The relative quantities of compounds a) and c) are preferably so chosenthat the ratio of the sum of the isocyanate groups in b) to the sum ofthe Tserevitinov-active hydrogen atoms in a) and c) amounts to 0.85:1 to1.2:1, particularly preferably 0.9:1 to 1.1:1.

The thermoplastic polyurethanes employed in accordance with theinvention may optionally contain catalysts d). Suitable catalysts arethe tertiary amines that are known and conventional in accordance withthe state of the art, such as, for example, triethylamine,dimethylcyclohexylamine, N-methylmorpholine, N,N′-dimethylpiperazine,2-(dimethylaminoethoxy)ethanol, diazabicyclo[2,2,2]octane and similarand also, in particular, organic metallic compounds such as titanic acidesters, iron compounds or tin compounds, such as tin diacetate, tindioctoate, tin dilaurate, or the dialkyltin salts of aliphaticcarboxylic acids, such as dibutyltin diacetate or dibutyltin dilaurateor similar. Preferred catalysts are organic metallic compounds, inparticular titanic acid esters, iron compounds and tin compounds. Thetotal quantity of catalysts in the thermoplastic polyurethanes amounts,as a rule, to about 0 wt. % to 5 wt. %, preferably 0 wt. % to 2 wt. %,relative to the total weight of the TPU.

The thermoplastic polyurethanes (TPU) employed in accordance with theinvention may optionally contain, by way of auxiliary substances andadditives e), 0 wt. % up to at most 20 wt. %, preferably 0 wt. % to 10wt. %, relative to the total weight of the TPU, of the conventionalauxiliary substances and additives. Typical auxiliary substances andadditives are pigments, dyestuffs, flame retardants, stabilisers againstthe influences of ageing and weathering, plasticisers, slip additives,mould-release agents, chain terminators, substances actingfungistatically and bacteriostatically and also fillers and mixturesthereof.

By way of such additives, inter alia compounds that are monofunctionalin relation to isocyanates may preferably be employed in proportions upto 2 wt. %, relative to the total weight of the thermoplasticpolyurethane, as so-called chain terminators or mould-release aids.Suitable are, for example, monoamines such as butylamine anddibutylamine, octylamine, stearylamine, N-methylstearylamine,pyrrolidine, piperidine or cyclohexylamine, monoalcohols such asbutanol, 2-ethylhexanol, octanol, dodecanol, stearyl alcohol, thevarious amyl alcohols, cyclohexanol and ethylene glycol monomethylether.

Examples of further additives are slip additives, such as fatty-acidesters, the metallic soaps thereof, fatty-acid amides, fatty-acid esteramides and silicone compounds, anti-blocking agents, inhibitors,stabilisers against hydrolysis, light, heat and discoloration, flameretardants, dyestuffs, pigments, inorganic and/or organic fillers, forexample polycarbonates, and also plasticisers and reinforcing agents.Reinforcing agents are, in particular, fibrous reinforcing substancessuch as, for example, inorganic fibres, which are produced in accordancewith the state of the art and which may also have been subjected to asizing material. Further particulars concerning the stated auxiliarysubstances and additives can be gathered from the specialist literature,for example from the monograph by J. H. Saunders and K. C. Frischentitled “High Polymers”, Volume XVI, Polyurethanes: Chemistry andTechnology, Parts 1 and 2, Interscience Publishers 1962 and 1964, fromthe Taschenbuch der Kunststoff-Additive by R. Gächter u. H. Müller(Hanser Verlag Munich 1990) or from DE-A 29 01 774.

The thermoplastic polyurethanes employed in accordance with theinvention preferably exhibit a hardness from 50 Shore D to 80 Shore D.The Shore hardness is determined in accordance with DIN EN ISO 868.

The thermoplastic polyurethanes employed in accordance with theinvention can be produced continuously in the so-called extruderprocess, for example in a multiple-shaft extruder, or in the so-calledbelt process. The metering of the TPU components a), b) and c) can beundertaken simultaneously, i.e. in the one-shot process, or insuccession, i.e. by means of a prepolymer process. The prepolymerprocess is particularly preferred. In this connection the prepolymer maybe produced both by charging in batches and continuously in a part ofthe extruder or in a separate upstream prepolymer unit, for example in astatic-mixer reactor, for example a Sulzer mixer.

The preferred polyester or copolyester, in particular copolyesteremployed in accordance with the invention preferably exhibits a glasstransition temperature T_(g) from 85° C. to 130° C., particularlypreferably from 90° C. to 120° C.

The polyester or copolyester, in particular copolyester employed inaccordance with the invention preferably exhibits an inherent viscosityfrom 0.50 dL/g to 0.80 dL/g.

Preferred copolyesters used in the present invention typically can beprepared by the reaction of terephthalic acid and optionally one or moreadditional difunctional carboxylic acids and/or multifunctionalcarboxylic acids—hereinafter referred to as dicarboxylic acidcomponent—with at least the two difunctional hydroxyl compounds2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1,4-cyclohexanedimethanoland optionally additional difunctional hydroxyl compounds and/ormultifunctional hydroxyl compounds—hereinafter referred to as diolcomponent. Typically the dicarboxylic acid component can be one or moredicarboxylic acid(s) and the diol compound can be two or more dihydricalcohols/glycols. The dicarboxylic acids and alcohols/glycols preferablyreact in substantially equal proportions and are incorporated into thecopolyester polymer as their corresponding residues. The copolyestersused according to the present invention, therefore, can containsubstantially equal molar proportions of acid residues and diolresidues.

The term “residue”, as used herein, means any organic structureincorporated into a polymer through a polycondensation and/or anesterification reaction from the corresponding monomer.

The dicarboxylic acid residues may be derived from a dicarboxylic acidmonomer or its associated acid halides, esters, salts, anhydrides, ormixtures thereof. As used herein, therefore, the term “dicarboxylicacid” is intended to include dicarboxylic acids and any derivative of adicarboxylic acid, including its associated acid halides, esters,half-esters, salts, half-salts, anhydrides, mixed anhydrides, ormixtures thereof, useful in a reaction process with a diol to make(co)polyester.

The dicarboxylic acid component in the particularly preferred embodimentcomprises 70 to 100 mole % of terephthalic acid residues, preferably 80to 100 mole % of terephthalic acid residues, more preferably 90 to 100mole % of terephthalic acid residues, most preferably 95 to 100 mole %of terephthalic acid residues. In a particularly preferred embodimentthe dicarboxylic acid component comprises 98 to 100 mole % ofterephthalic acid residues. In another particularly preferred embodimentthe dicarboxylic acid component comprises 100 mole % of terephthalicacid residues.

The total mole % of the dicarboxylic acid component is 100 mole %.

Esters and/or salts of the modifying dicarboxylic acids may be usedinstead of the dicarboxylic acids. Suitable examples of dicarboxylicacid esters include, but are not limited to, the dimethyl, diethyl,dipropyl, diisopropyl, dibutyl, and diphenyl esters. In one embodiment,the esters are chosen from at least one of the following: methyl, ethyl,propyl, isopropyl, and phenyl esters.

The ratio of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and1,4-cyclohexanedimethanol residues from the diol component of thecopolyester preferably amounts to 10 mole % to 35 mole %2,2,4,4-tetramethyl-1,3-cyclobutanediol residues to 65 mole % to 90 mole% 1,4-cyclohexanedimethanol residues, particularly preferably 15 mole %to 35 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues to 65 mole% to 85 mole % 1,4-cyclohexanedimethanol residues, quite particularlypreferably 15 mole % to 30 mole %2,2,4,4-tetramethyl-1,3-cyclobutanediol residues to 70 mole % to 85 mole% 1,4-cyclohexanedimethanol residues, whereby the sum of the mole % ofthese two components of the diol component amounts to 100 mole %.

The diol component of the copolyester(s) in the particularly preferredembodiment can contain 25 mole % or less of one or more modifying diolswhich are not 2,2,4,4-tetramethyl-1,3-cyclobutanediol or1,4-cyclohexanedimethanol. In one embodiment, the copolyesters useful inthe invention may contain 15 mole % or less of one or more modifyingdiols. In another embodiment, the copolyesters useful in the inventioncan contain 10 mole % or less of one or more modifying diols. In anotherembodiment, the copolyesters useful in the invention can contain 5 mole% or less of one or more modifying diols. In another embodiment, thecopolyesters useful in the invention can contain 3 mole % or less of oneor more modifying diols. In another embodiment, the copolyesters usefulin the invention can contain 0 mole % modifying diols. Certainembodiments can also contain 0.01 or more mole %, such as 0.1 or moremole %, 1 or more mole %, 5 or more mole %, or 10 or more mole % of oneor more modifying diols. Thus, if present, it is contemplated that theamount of one or more modifying diols can range from any of thesepreceding endpoint values including, for example, from 0.01 to 15 mole %and preferably from 0.1 to 10 mole %.

Modifying diols useful in the copolyester(s) useful in the inventionrefer to diols other than 2,2,4,4,-tetramethyl-1,3-cyclobutanediol and1,4-cyclohexanedimethanol and may contain 2 to 16 carbon atoms. Examplesof suitable modifying diols include, but are not limited to, ethyleneglycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol,1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, p-xylene glycol ormixtures thereof. Preferred modifying diols, if present, are ethyleneglycol, 1,3-propanediol and/or 1,4-butanediol.

Each of the diols 2,2,4,4-tetramethyl-1,3-cyclobutanediol or1,4-cyclohexanedimethanol may be cis, trans, or a mixture thereof.

For the desired copolyester, the molar ratio of cis/trans2,2,4,4-tetramethyl-1,3-cyclobutanediol can vary from the pure form ofeach or mixtures thereof. In certain embodiments, the molar percentagesfor cis and/or trans 2,2,4,4-tetramethyl-1,3-cyclobutanediol are greaterthan 50 mole % cis and less than 50 mole % trans; or greater than 55mole % cis and less than 45 mole % trans; or 30 to 70 mole % cis and 70to 30 mole % trans; or 40 to 60 mole % cis and 60 to 40 mole % trans;wherein the total sum of the mole percentages for cis- andtrans-2,2,4,4-tetramethyl-1,3-cyctobutanediol is equal to 100 mole %.

For the desired copolyester, the molar ratio of1,4-cyclohexanedimethanol can vary from the pure form of each ormixtures thereof. By using a mixture of cis and trans the molar ratio ofcis/trans 1,4-cyclohexanedimethanol can vary within the range of 50/50to 0/100, for example, between 40/60 to 20/80.

The poly- or copolyester useful in the invention can be made byprocesses known from the literature such as, for example, by processesin homogenous solution, by transesterfication processes in the melt, andby two phase interfacial processes. Suitable methods include, but arenot limited to, the steps of reacting one or more dicarboxylic acidswith one or more diols at a temperature of 100° C. to 315° C. at apressure of 0.13 mbar to 1011 mbar (0.1 to 760 mm Hg) for a timesufficient to form a polyester. See U.S. Pat. No. 3,772,405 orKunststoff-Handbuch, Vol. VIII, p. 695 ff, Karl-Hanser-Verlag, Munich1973 for methods of producing (co)polyesters.

Suitable polycarbonates or copolycarbonates useful in the invention arecommercially available, for example under the trademark Makrolon® fromBayer MaterialScience AG. Suitable polyesters or copolyesters useful inthe invention are also commercially available, for example under thetrademark Skygreen from SK Chemical or Tritan™ from Eastman ChemicalCompany. Suitable thermoplastic polyurethanes useful in the inventionare also commercially available, e.g. from Bayer MaterialScience AG.

The plastic film according to the invention preferably exhibits a totalthickness from 300 μm to 2000 μm, particularly preferably from 400 μm to1500 μm, quite particularly preferably from 500 μm to 1200 μm.

In the case of the plastic film according to the invention, in apreferred embodiment it is a question of a three-layer film consistingof the core layer A between the two outer layers B.

This preferred embodiment of the plastic film according to the inventiondisplays an excellent adhesion between the core layer A, particularlypreferred the copolyester core layer A, and the outer layers B,particularly preferred the TPU outer layers B. Good adhesion betweenthese layers is particularly advantageous and necessary, since adelamination of the plastic film during its use in a wet or humidityenvironment is undesirable. Moreover, after the production ofthree-dimensional shaped articles e.g. by means of thermoforming of thefilm according to the invention and trimming on the cut edges, thearticles have to be ground. Also in the course of this grinding processa delamination of the individual layers is undesirable.

The adhesive force between the core layer A and the outer layers Bpreferably amounts to more than 0.3 N/mm, preferably more than 0.5 N/mmAdhesive force can be determined in accordance with ASTM D 903 98.

The core layer A of the plastic film according to the inventionpreferably exhibits a layer thickness from 250 μm to 1600 μm,particularly preferably from 350 μm to 1400 μm, quite particularlypreferably from 400 μm to 1000 μm. The outer layers B of the plasticfilm according to the invention preferably exhibit in each instance alayer thickness from 25 μm to 500 μm, particularly preferably from 30 μmto 300 μm, quite particularly preferably from 50 μm to 200 μm.

For some application e.g. for medical applications it is, inter alia,also desirable that the film for the production of the shaped articlesis as inconspicuous as possible during the course of usage. Therefore itis furthermore advantageous if the plastic film is as transparent aspossible. This requirement is likewise satisfied by the film accordingto the invention.

The plastic film according to the invention preferably exhibits atransmission of visible light within the wavelength range from 380 nm to780 nm of more than 70%, particularly preferably of more than 80%. Thetransmission can be determined in accordance with ASTM D 1003—forexample, with an Ultra Scan XE produced by Hunter Associates LaboratoryInc.

The plastic film according to the invention can be produced by means ofco-extrusion or double lamination. Production by means of co-extrusionis preferred.

The production of multi-layer plastic films by means of co-extrusion isknown to a person skilled in the art. In this connection, for therespective plastic layers the respective plastics, for example andpreferably in the form of granular materials, are fused in a compoundingextruder and are extruded into a film via a nozzle.

In the course of the double lamination, firstly two films are producedfor the two outer layers B, preferentially by means of extrusion, andthe core layer A is produced by running the melt in between these twoplastic films.

By reason of their outstanding properties—such as, for example, slightdrop in the tensile modulus, stability in its three-dimensional shapeand good transparency—the plastic films according to the invention areparticularly well suited for the purpose of producingthree-dimensionally shaped articles. For the purpose of producing such3D-shaped articles, shaping into the appropriate shape is effected bymeans of thermoforming from the plastic films according to theinvention, and the latter is subsequently cut and polished.

Therefore, a further object of the present invention is athree-dimensionally shaped article obtained from the multi-layered filmaccording to the present invention, in particular by means ofthermoforming.

The plastic films according to the invention are particularly wellsuited for the purpose of producing three-dimensionally shaped articles,in particular for use in medical applications, such as for orthopaedicdevices, e.g. orthopaedic supports, dental devices, e.g. dental splintsor retainers, or splints, e.g. for stabilizing sprained joints orfractures. Additionally the plastic films according to the invention areparticularly well suited for the purpose of producingthree-dimensionally shaped articles for non-medical applications, suchas photovoltaic or (underfloor) heating applications. Moreover, theplastic films according to the invention could particularly be wellsuited for bullet-proof glass laminates.

The following Examples serve for exemplary elucidation of the inventionand are not to be interpreted as limitation.

EXAMPLES Feed Materials

ISOPLAST 2530: commercial aromatic transparent thermoplasticpolyurethane for medical applications with a Shore hardness of 82 Daccording to DIN EN ISO 868 (Lubrizol Corp.)

DESMOPAN DP 9365 D: commercial aromatic transparent thermoplasticpolyether polyurethane with a Shore hardness of 65 D according to DIN ENISO 868 (Bayer MaterialScience AG)

Copolyester I: Copolycondensate of terephthalic acid consisting of 48.4wt. % terephthalic acid, 11.9 wt. % (23 mole % relative to the diolcomponent) 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 39.7 wt. % (77mole % relative to the diol component) cyclohexanedimethanol, with aninherent viscosity of 0.72 dl/g (measured in a 1:1 mixture consisting ofphenol and tetrachloroethane at 25° C.) (Eastman Chemical), Glasstransition temperature 110° C. (determined by DSC)

Copolyester II: Copolycondensate of terephthalic acid consisting of 48.3wt. % terephthalic acid, 11.7 wt. % (23 mole % relative to the diolcomponent) 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 40.0 wt. % (77mole % relative to the diol component) cyclohexanedimethanol, with aninherent viscosity of 0.63 dl/g (measured in a 1:1 mixture consisting ofphenol and tetrachloroethane at 25° C.), Glass transition temperature105° C. (determined by DSC)

TEXIN 970U: commercial aromatic transparent thermoplastic polyetherpolyurethane with a Shore hardness of 70 D according to DIN EN ISO 868(Bayer MaterialScience AG)

MAKROLON 3108: commercial high viscous amorphous, thermoplasticBisphenol A-Polycarbonat with a Melt Volume Rate (MVR) of 6 g/10 minaccording to ISO 1133 at 300° C. and 1.2 kg from Bayer MaterialScienceAG; Glass transition temperature 149° C. (determined by DSC)

HYTREL 7246: is a commercial high modulus thermoplastic polyesterelastomer grade with nominal Shore hardness according to DIN EN ISO 868of 72 D from Dupont Company, Wilmington

POCAN B 1600: is a commercial thermoplastic butylene terephthalate witha Melt Volume Rate (MVR) of 14 g/10 min according to ISO 1133 at 260° C.and 2,16 kg from Lanxess AG

Production of the Layered Structures According to the Invention:Production of Extruded Films

The film extrusion line that is used for producing the co-extrudedfilm(s) comprises:

-   -   an extruder with a screw of 60 mm diameter (D) and with a length        of 33 D. The screw exhibits a degassing zone;    -   a melt pump;    -   a crosshead;    -   a flat sheet die with a width of 450 mm;    -   a three-roll calender with horizontal roller arrangement, the        third roller being capable of swivelling about +/−45° in        relation to the horizontal;    -   a roller conveyor;    -   thickness measurement    -   a device for bilateral application of protective film;    -   a take-off device;    -   a winding machine.

The granular material was conveyed out of the dryer into the feed hopperof the extruder. In the plasticising system constituted by thecylinder/screw of the extruder the melting and conveying of the materialtook place. From the flat sheet die the melt arrived at the calender. Onthe calender (consisting of three rolls) the definitive shaping andcooling of the film took place. For the purpose of texturing thesurfaces of the film, in this connection two polished chromium rollers(for gloss/gloss surfaces) were employed. Subsequently the film wastransported through a take-off, the protective film is applied on bothsides, then the winding-up of the film took place.

Example 1 Not According to the Invention

With the film extrusion line described above, with a temperature of themain extruder from 240° C. to 260° C. a monolayer film consisting ofCopolyester I with a thickness of 760 μm was produced.

Example 2 Not According to the Invention

With the same film extrusion line as in Example 1, with a temperature ofthe main extruder from 220° C. to 240° C. a monolayer film consisting ofISOPLAST 2530 with a thickness of 750 μm was produced.

Example 3 According to the Invention Co-Extrusion of Film

The film extrusion line that is used consists of

-   -   an extruder with a screw of 105 mm diameter (D) and with a        length of 41×D. The screw exhibits a degassing zone;    -   a co-extruder for applying the top layer with a screw of length        25 D and with a diameter of 35 mm    -   a crosshead;    -   a special co-extrusion film die with a width of 1500 mm;    -   a three-roll calender with horizontal roller arrangement, the        third roller being capable of swivelling about +/−45° in        relation to the horizontal;    -   a roller conveyor;    -   a device for application of protective film on both surfaces;    -   a take-off device;    -   winding machine.

The granular material of the base material was supplied to the feedhopper of the main extruder. In the respective plasticising systemconstituted by cylinder/screw the melting and conveying of therespective material took place.

Both material melts were brought together in the co-extrusion nozzle.From the nozzle the melt arrived at the calender. On the roll calenderthe definitive shaping and cooling of the material take place. For thepurpose of structuring the surfaces of the film, in this connection twopolished chromium rollers (for gloss/gloss surfaces) were employed.Subsequently the film was transported through a take-off, the protectivefilm is applied on both sides, then the winding-up of the film tookplace.

With this film extrusion line, with a temperature of the main extruderfrom 220° C. to 240° C. and with a temperature of the co-extruder from228° C. to 260° C. three-layer films according to the invention with twosmooth, glossy sides with a layer thickness of 800 μm were extruded, thecopolyester core layer being 650 μm thick and the thermoplasticpolyurethane layer on each side being in each instance 75 μm thick.

Example 4 According to the Invention

In the film extrusion line as in Example 3, instead of Copolyester I themore readily flowing Copolyester II was employed for the purpose ofproducing the three-layer films.

From this, with a temperature of the main extruder from 220° C. to 235°C. and with a temperature of the co-extruder from 227° C. to 260° C.three-layer films according to the invention with two smooth, shinysides with a layer thickness of 800 μm were extruded, the copolyestercore layer being 650 μm thick and the thermoplastic polyurethane layeron each side being in each instance 75 μm thick.

Example 5 According to the Invention

In the same film extrusion line as in Example 3, a film according to theinvention with one glossy surface and one matt surface was extruded.

In this connection, for the purpose of structuring the two surfaces ofthe film a polished chromium roller and a structured silicone-rubberroller were employed. Rubber rollers that are used for the structuringof the surface of the film are described in DE 32 28 002 (or in theequivalent U.S. Pat. No. 4,368,240) held by Nauta Roll Corporation.

With a temperature of the main extruder from 220° C. to 235° C. and witha temperature of the co-extruder from 227° C. to 260° C. three-layerfilms according to the invention with a smooth, glossy side and with amatt side with a layer thickness of 800 μm were extruded, thecopolyester core layer being 650 μm thick and the thermoplasticpolyurethane layer on each side being in each instance 75 μm thick.

Example 6 According to the Invention

In the film extrusion line as in Example 3, instead of Copolyester I theblend of 60% by weight MAKROLON 3108 and 40% by weight POCAN B 1600 forthe main extruder and TEXIN 970U for the co extruder were employed forthe purpose of producing the three-layer films. The TEXIN 970U forms theouter layers, the MAKROLON/POCAN blend the core layer.

From this, with a temperature of the main extruder from 260° C. to 270°C. and with a temperature of the co-extruder from 210° C. to 230° C.three-layer films according to the invention with two smooth, shinysides with a layer thickness of 750 μm were extruded, the copolyestercore layer being 550 μm thick and the thermoplastic polyurethane layeron each side being in each instance 100 μm thick.

Example 7 According to the Invention

In the film extrusion line as in Example 3, instead of Copolyester I theblend of 60% by weight MAKROLON 3108 and 40% by weight POCAN B 1600 forthe main extruder and HYTREL 7246 for the co extruder were employed forthe purpose of producing the three-layer films. The HYTREL 7246 formsthe outer layers, the MAKROLON/POCAN blend the core layer.

From this, with a temperature of the main extruder from 260° C. to 270°C. and with a temperature of the co-extruder from 227° C. to 245° C.three-layer films according to the invention with two smooth, shinysides with a layer thickness of 750 μm were extruded, the copolyestercore layer being 550 μm thick and the thermoplastic polyester elastomerlayer on each side being in each instance 100 μm thick.

Example 8 According to the Invention

In the film extrusion line as in Example 3, instead of Copolyester I theblend of 60% by weight MAKROLON 3108 and 40% by weight POCAN B 1600 forthe main extruder and ISOPLAST 2530 for the co extruder were employedfor the purpose of producing the three-layer films. The ISOPLAST 2530forms the outer layers, the MAKROLON/POCAN blend the core layer.

From this, with a temperature of the main extruder from 260° C. to 270°C. and with a temperature of the co-extruder from 210° C. to 240° C.three-layer films according to the invention with two smooth, shinysides with a layer thickness of 750 μm were extruded, the copolyestercore layer being 550 μm thick and the thermoplastic polyurethane layeron each side being in each instance 100 μm thick.

Example 9

Method for determining the peel strength of the thermoplasticpolyurethane (TPU) layer on the copolyester layer of examples 3 to 5

Preparation of the Specimens:

-   -   1. Die-cut specimens to 4 inch L×0.76 inch W (10 mm L×19.3 mm        W): Die dimension can vary depending on availability (W: 0.75˜1        inch, L: minimum 4 inch).    -   2. Mark on the side of the TPU layer being tested. Flip the        sample to the other side. Scratch a line by a sharp cutter at 7        mm from one edge of the specimen.    -   3. Gently bend the specimen along the cut line while having the        tested TPU layer intact.    -   4. Gently start peeling the TPU layer by pulling the small cut        portion away from the cut line.    -   5. Continue peeling until the peel TPU layer is 13 mm in length.        Make sure the TPU layer is peeled uniformly across the whole        specimen width.    -   6. Cut the other end of the specimen to make the total adhered        area be 62 mm in length.

Example 10 Determination of the Peel Strength Method:

The determination of the peel strength was carried out following themodel of ASTM D 903 98. The specimens, which were prepared in accordancewith the method in Example 6, were stored at 50% relative humidity and23° C. and subsequently tested under these conditions. The separationrate amounted to 305 mm/min From the calibration curves the mean valuebetween 5 mm and 25 mm was evaluated.

The determination has been carried out at three different positions ofthe specimen. The following show the calculated average results.

For the bottom layer an average load per unit width of 0.76 N/mm forexample 3, 0.79 N/mm for example 4 and 0.97 N/mm for example 5 wasmeasured. For the top layer an average load per unit width of 1.13 N/mmfor example 3, 0.60 N/mm for example 4 and 1.10 N/mm for example 5 wasmeasured. The results show that the films according to the inventionexhibit an excellent adhesion between the copolyester core layer and theTPU outer layers.

For the three-layered films according to example 6 to 8 the peelstrength between the outer layers and the core layer were so high thatno separation without damage of the outer layer was possible, so thatalso these films according to the invention exhibit an excellentadhesion between the core layer and the outer layers.

Example 11 Method for Determination of Tensile Strength

The measure of tensile strength was carried out following the model ofASTM D 638. The tensile tests were carried out on a tensile testingmachine of the type ZwickZ020/148385. Use was made of tensile testspecimens of type 4. For the purpose of evaluation, the mean value of 5measurements was drawn upon. The specimens were stored at >48 hours at50% relative humidity and 23° C. and subsequently tested under theseconditions. The speed of testing amounted to 12.7 mm/min, in the courseof the determination of Young's modulus (elastic modulus or modulus ofelasticity), 1 mm/min.

The determination has been carried out at three different positions ofthe specimen. The following table show the calculated average results.

Results:

average average average yield average tensile average tensile stressyield strength elongation modulus Example (N/mm²) strain (%) (N/mm²) atbreak (%) (N/mm²) 3 36.0 6.6 54.7 168.7 1233.0 4 36.3 6.3 53.5 171.61246.0 5 35.7 6.3 56.6 183.4 1249.0 6 32.4 4.3 40.4 128.8 1069 7 34.94.2 58.4 193.4 1202 8 39.6 4.2 56.4 180.2 1157

The results show that the films according to the invention exhibit anexcellent tensile strength and an outstanding tensile modulus.

Example 12 Method for Determining the Stress Relaxation

The stress relaxation has been determined according to a modification ofASTM D790:

-   -   sample dimensions: 51 mm (length)×21.5 mm (width)λ ˜0.8 mm        (thickness)    -   water soaking of the samples at defined temperature (25° C. or        50° C.) before measurement of stress relaxation    -   three-point bending with 5% strain    -   support span: 16 mm

Results:

Water Initial load Remaining % Re- Temperature (N) (t = 0 Load (N)maining (° C.) Materials hour) (t = 24 hours) Load 25° C. Example 2 45.817.7 39 (not according to the invention)) Example 3 25.7 18.3 71(according to the invention) Example 6 45 26.9 60 (according to theinvention) Example 7 35.5 21.4 60 (according to the invention) Example 851.1 24 47 (according to the invention) 50° C. Example 2 39.6 2.05 5(not according to the invention)) Example 3 20.7 4.5 22 (according tothe invention) Example 6 32.9 11 33 (according to the invention) Example7 27.4 11.2 41 (according to the invention) Example 8 39.7 6.5 16(according to the invention)

In this connection the values for initial load represent the measuredvalues at the time prior to storage, i.e. at time t=0, and the valuesfor remaining load represent the measured values at the time after 24 hof storage.

The results show that at both storage temperatures the three-layer filmsaccording to the invention exhibited a higher remaining load after 24 hstorage than the TPU single-layer film from Example 2. In particular forexamples 3 and 7 it is the more surprising that—although at both storagetemperatures the three-layer film according to the invention exhibited adistinctly lower initial load at the time prior to storage—the forcethat it was still able to exert after storage after 24 h fell to aconsiderably slighter extent.

Only the samples consisting of the three-layer films according to theinvention exhibit a small drop in the tensile modulus during the storagein the wet environment. In addition, the films according to theinvention display an outstanding adhesion between the core layers andthe other layers.

Although the invention has been described in detail in the foregoing forthe purpose of illustration, it is to be understood that such detail issolely for that purpose and that variations can be made therein by thoseskilled in the art without departing from the spirit and scope of theinvention except as it may be limited by the claims.

1. Multi-layer plastic film, comprising a core layer A comprising atleast one polycarbonate or copolycarbonate and/or a polyester orcopolyester having a glass transition temperature T_(g) from 80° C. to200° C., said core layer A being located between two outer layers Bcomprising at least one thermoplastic polyurethane and/or polyester orcopolyester exhibiting a hardness from 45 Shore D to 85 Shore D. 2.Multi-layer plastic film according to claim 1, wherein said a core layerA comprises at least one polyester or copolyester having an inherentviscosity from 0.50 dL/g to 1.20 dL/g and a glass transition temperatureT_(g) from 80° C. to 200° C.
 3. Multi-layer plastic film according toclaim 1, wherein the two outer layers B comprise at least onethermoplastic polyurethane exhibiting a hardness from 45 Shore D to 85Shore D.
 4. Multi-layer plastic film according to at least claim 1,wherein a said core layer A comprises at least one copolyester thatexhibits residues from (a) a dicarboxylic acid component comprising i)70 mole % to 100 mole % terephthalic acid residues, ii) 0 mole % to 30mole % aromatic dicarboxylic acid residues with up to 20 carbon atoms,and iii) 0 mole % to 10 mole % aliphatic dicarboxylic acid residues withup to 16 carbon atoms, and (b) a diol component comprising i) 5 mole %to 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues, and ii)50 mole % to 95 mole % 1,4-cyclohexanedimethanol residues, wherein thesum of the mole % of residues i)-iii) of the dicarboxylic acid componentamounts to 100 mole % and the sum of the mole % of residues i) and ii)of the diol component amounts to 100 mole % and wherein the inherentviscosity of the copolyester amounts to 0.50 dL/g to 1.20 dL/g and thecopolyester exhibits a glass transition temperature T_(g) from 80° C. to150° C., and wherein said core layer is located between two outer layersB comprising at least one thermoplastic polyurethane, the thermoplasticpolyurethane exhibiting a hardness from 45 Shore D to 85 Shore D andbeing obtainable from a) one or more linear polyether diols with meanmolecular weights from 500 g/mol to 10,000 g/mol, optionally 500 g/molto 6000 g/mol, and, on average, in each instance at least 1.8 and atmost 3.0, optionally 1.8 to 2.2, Tserevitinov-active hydrogen atoms b)one or more organic diisocyanates, c) one or more diol chain-extenderswith molecular weights from 60 g/mol to 500 g/mol and with, on average,1.8 to 3.0 Tserevitinov-active hydrogen atoms in the presence of d)optionally, one or more catalysts with addition of e) optionally, one ormore auxiliary substances and additives, wherein the molar ratio of theNCO groups in b) to the groups in a) and c) that are reactive towardsisocyanate amounts to 0.85:1 to 1.2:1, optionally 0.9:1 to 1.1:1. 5.Multi-layer plastic film according to claim 1, wherein the thermoplasticpolyurethane exhibits a hardness from 50 Shore D to 80 Shore D. 6.Multi-layer plastic film according to claim 4, wherein the polyetherdiol a) used for producing the thermoplastic polyurethane is selectedfrom one or more polyether diols of the group based on 1,4-butanediolunits and/or 1,3-propylene glycol units.
 7. Multi-layer plastic filmaccording to claim 4, wherein the organic diisocyanate b) used forproducing the thermoplastic polyurethane is selected from one or moreisocyanates of the group containing 4,4′-diphenylmethane diisocyanate,isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate or1,6-hexamethylene diisocyanate.
 8. Multi-layer plastic film according toclaim 4, wherein the diol chain-extender c) used for producing of thethermoplastic polyurethane is selected from one or more chain-extendersof the group containing 1,4-butanediol, 1,3-propanediol,1,2-propanediol, 1,2-ethylene glycol, 1,6-hexanediol,1,4-di(β-hydroxyethyl)hydroquinone or 1,4-di(β-hydroxyethyl)bisphenol A.9. Multi-layer plastic film according to claim 4, wherein thethermoplastic polyurethane was produced in a prepolymer process. 10.Multi-layer plastic film according to claim 4, wherein the diolcomponent of the copolyester comprises 10 mole % to 35 mole %2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and 65 mole % to 90mole % 1,4-cyclohexanedimethanol residues, optionally 15 mole % to 35mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and 65 mole % to85 mole % 1,4-cyclohexanedimethanol residues, or optionally 15 mole % to30 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and 70 mole %to 85 mole % 1,4-cyclohexanedimethanol residues, the sum of the mole %of these two components of the diol component amounting to 100 mole %.11. Multi-layer plastic film according to claim 4, wherein the residuesfrom the dicarboxylic acid component of the polyester include 95 mole %to 100 mole % terephthalic acid residues.
 12. Multi-layer plastic filmaccording to claim 1 wherein the film has been co-extruded. 13.Multi-layer plastic film according to claim 1, comprising a totalthickness from 300 μm to 2000 μm, optionally from 400 μm to 1500 μm, oroptionally from 500 μm to 1200 μm.
 14. Multi-layer plastic filmaccording to claim 1, wherein the core layer A has a layer thicknessfrom 250 μm to 1600 μm, preferably optionally from 350 μm to 1400 μm, oroptionally from 400 μm to 1000 μm.
 15. Multi-layer plastic filmaccording to claim 1 wherein the outer layers B each have a layerthickness from 25 μm to 500 μm, optionally from 30 μm to 300 μm, oroptionally from 50 μm to 200 μm.
 16. Multi-layer plastic film accordingto claim 2, wherein the poly- or copolyester exhibits an inherentviscosity from 0.50 dL/g to 0.80 dL/g.
 17. Multi-layer plastic filmaccording to claim 1, wherein the poly- or copolyester exhibits a glasstransition temperature T_(g) from 85° C. to 130° C., optionally from 90°C. to 120° C.
 18. Three-dimensionally shaped article obtained bythree-dimensionally forming the multi-layer plastic film according toclaim 1.